(1) Field of the Invention
This invention relates to very small and thin transformers for communication to be used as incorporated in such electronic devices as,for example, miniature facsimiles, modems and miniature terminal devices having modem functions and more particularly to a miniature transformer provided with an insulating cover having a function of pressing in the laminating direction a core incorporated as laminated in a coil bobbin.
(2) Description of the Prior Art
In a transformer in the prior art, a laminated core is incorporated and is provided with an insulating cover which has been used in order to secure a surface and spatial distance solely among a primary coil, secondary coil and core.
This thin transformer is so small as to be, for example, 13 cm long vertically, 16 cm long horizontally and 3 cm thick and the number of laminations to be incorporated into the core is so few as to be about 4 to 14 sheets in case the core sheet is 0.15 mm thick and to be about 3 to 8 sheets in case it is 0.20 mm thick. When a gap is produced between the laminations incorporated in the core, such transmission characteristics as impedance characteristics and frequency characteristics in the case of a transmission transformer will be deteriorated, the transmission waveform will be deteriorated and such adverse influences will be produced on the electric characteristics of the transformer. Therefore, it is necessary to intimately bond the core laminations without a gap between them.